Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users

Abstract Introduction: Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol, but supportive data in humans is scarce. Purpose: The present study was designed to assess tolerance and cross-tolerance to the neurocognitive effects of THC and alcohol in heavy cannabis users. Methods: Twenty-one heavy cannabis users participated in a double-blind, placebo-controlled, three-way